Steering All Over the Place at 55mph+

lots of good stuff above. I had the same issue with my 71 Dodge Demon and I replaced everything except for the upper and lower control arms themselves. Besides the wandering issue above 60 or so I recently noticed extreme front tire wear despite the fact I had aligned it to -5 camber and 2.2 caster (all I could get out of it). So when I noticed the front tires were so worn in just 400 miles, I checked my alignment only to find it was way way off from those numbers (which stink in my opinion). I tried everything but the best caster I could get was 1 degree on the passenger side. I ended up ordering QA-1 upper and lower control arms and their dynamic adjustable strut rods for around $1100 from Summit. Their control arms are advertised to give like 4 extra degrees of caster if my memory is correct. The original lower control arm was extremely worn on the pivot bushing. I just got the new parts today but its like night and day as far as the slop the original lower control arm had and how nice and stiff the new one is. I think the torsion bar scares a lot of people so few people de-tension and check that but I would take a look at that for sure.